1. Field of the Invention
The present invention relates to a torque transmission device for an automatic power transmission for an automotive vehicle. More specifically, the invention relates to a torque transmission device which is capable of absorption of torsional vibration induced by an engine output fluctuation.
2. Description of the Background Art
In the recent years, there has been developed and proposed a torque transmission system between an automotive internal combustion engine and a torque converter of an automatic power transmission, which can absorb shock induced by an engine output fluctuation. Such torque transmission device employs a torsion damper interposed between a crankshaft as the output element of the internal combustion engine and a converter cover which serves as an input element of the torque converter. One example of such type of the torque transmission device has been disclosed in the Japanese Utility Model First (unexamined) Publication 58-79156.
Such prior proposed torque transmission devices are not at all satisfactory in damping torsional vibration induced on the crankshaft. Especially, the torsional vibration on the crankshaft influences vehicular body vibration and vehicular cabin noise when the automatic power transmission operates in a lock-up mode, in which the crankshaft is directly and mechanically coupled with an input shaft of the power transmission. Transmission of torsional vibration from the crankshaft to the power transmission may cause an uncomfortable vehicular body vibration and noise to degrade vehicular riding comfort.